In order to elucidate the molecular mechanisms underlying the nerve impulse it is proposed to study three major functional asymmetries of nerve membrane using internally perfused voltage clamped squid giant axons. First the asymmetries of the ionic conductance mechanisms will be studied by varying the ionic composition of the two media. Then the asymmetric displacement currents or gating currents will be measured and compared to asymmetries in the change in optical retardation or birefringence.